<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>matchesSelector</title>
</head>
<body>
<div class="a">dom扩展</div>
<button>troubleMaker</button>
<script>
    console.log(document.querySelector(".a").innerHTML);
    console.log(document.getElementsByClassName("a")[0].innerHTML);
    console.log(document.querySelector("button").innerHTML);
    console.log(document.getElementsByTagName("button")[0].innerHTML);

//    这两个方法和matchesSelector有关系，但是没看懂这玩意咋用
//    querySelector方法直接搞定了elementsByClassName、elementById、elementsByTagName,方便了很多
</script>
</body>
</html>